Control of nosocomial infection and exposure to infectious disease is of paramount concern to doctors, nurses, and clinicians who work in hospitals and surgery centers. One of the most effective methods for controlling infection is regimented hand disinfection before and possibly after each patient contact and particularly before and after each surgical procedure. Hand disinfection is generally accomplished using antimicrobial soaps with water. These soaps are usually formulated to include either povidone-iodine (usually 7.5% by weight) or chlorhexidine digluconate (CHG) (usually 2% or 4% by weight) as the active antimicrobial agent. In addition, these formulated soaps may contain surfactants and possibly low levels of humectants such as glycerin.
Hand disinfection is also accomplished using presurgical scrub replacements. These are used instead of the soap and water scrub. Presurgical scrub replacements ideally achieve bacterial kill equal to or better than a traditional soap and water scrub and in a shorter period of time. Additionally, they maintain or improve the skin's natural barrier to microbial and chemical contamination while providing acceptable tactile properties. Examples of presurgical scrub replacements include hydroalcoholic gels which generally include high levels of either ethanol or isopropanol as the disinfecting agent and also include a thickener and optionally a humectant (e.g., glycerin).
To date, thickeners used in hydroalcoholic gels have been based primarily on anionic polymers such as polyacrylic acid (sold under the tradename “CARBOPOL” by B F Goodrich Specialty Polymers and Chemicals Division of Cleveland, Ohio). See, for example, U.S. Pat. Nos. 4,956,170 (Lee) and 5,167,950 (Lins). These compositions are generally incompatible with cationic compounds such as chlorhexidine gluconate. There are a few reports of nonionic and cationic-polymeric thickeners being used as well. See, for example, U.S. Pat. No. 4,478,853 (Chausee) and International Publication No. WO 93/007903 (Deckner). These hydroalcoholic compositions have relatively low levels of alcohol, generally too low to provide rapid and effective antimicrobial activity.
U.S. Pat. No. 5,512,199 (Khan) discloses a hydroalcoholic wipe composition, incorporating nonionic and cationic polymeric emollients or humectants. These compositions have very low viscosities, too low to be used as a lotion. U.S. Pat. Nos. 4,915,934 (Tomlinson) and 4,981,698 (Tomlinson) provide hydroalcoholic biocidal compositions incorporating low molecular weight polymeric emollients such as polyglycerol and polyvinyl pyrrolidone. These polymers do not provide adequate thickening in hydroalcoholic lotions.
In other hydroalcoholic systems, such as those described in U.S. patent application Ser. Nos. 08/493,714 and 08/493,695 (both of which were filed on Jun. 22, 1995 and assigned to 3M Company), nonionic, anionic, cationic, or zwitterionic emulsifiers are used as thickeners for a wide range of concentrations of alcohol, without the need for a polymeric thickener such as polyacrylic acid. Although these systems are highly desirable, other high viscosity hydroalcoholic compositions useful as an antimicrobial lotion, for example, are still needed.